Coal liquefaction

ABSTRACT

Normally solid coal is hydrogenated using certain supported hydrogenation catalysts in the substantial absence of externally supplied liquid slurry medium and in a catalyst/coal weight ratio of from about 0.1/1 to about 2/1.

United States Patent Robert W. Rieve Harold Shalit, Drexel Hill, both ofPa. 88,1 18

Nov. 9, 1970 Nov. 9, 1971 Atlantic Richiield Company New York, N.Y.

[72] Inventors [21 Appl. No. [22] Filed [45] Patented [73] Assignee [54]COAL LIQUEFACTION 6 Claims, No Drawings [56] References Cited PrimaryExaminer-Delbert E. Gantz Assistant ExaminerVeronica OKeefeAttorneys-Blucher S. Tharp and Roderick W. MacDonald ABSTRACT: Normallysolid coal is hydrogenated using certain supported hydrogenationcatalysts in the substantial absence of externally supplied liquidslurry medium and in a catalyst/coal weight ratio of from about 0.1/1 toabout 2/ l.

com. LIQUEFACTION BACKGROUND OF THE INVENTION Heretofore nonnally solid,subdivided coal has been converted into a combination of gaseoushydrocarbonaceous and liquid hydrocarbonaceous products by subjectingthe coal to hydrogenation under elevated temperatures and pressure inthe presence of a liquid slurry medium (solvent).

The hydrogenation slurry medium (hereinafter slurry medium) is normallya hydrocarbonaceous liquid oil previously obtained from the liquefactionof coal but can be other hydrocarbonaceous liquids as desired and aswell known in the art.

A particularly useful coal liquefaction process is fully and completelydisclosed in US. Pat. Re. 25,770, the disclosure of which isincorporated herein by reference. Generally, the slurry medium is acomplex hydrocarbonaceous liquid having a boiling range within the rangeof from the boiling temperature of butane to about l,500 F. and containsone or more of naphtha boiling in a range of from the boiling point ofbutane to about 400 F., light distillate boiling in the range of fromabout 400 .to about 650 F., heavy distillate boiling in the range offrom about 650 to about 975 F., and residual fuel oil boiling in therange of from about 975 to about l,500 F.

The hydrogenation medium medium normally employed in a slurrymedium/coal weight ratio of from about 0.1/1 to about 4/1 so that thereis always substantial amounts of liquid slurry medium present in thehydrogenation operation.

Various catalysts have been used, generally in catalyst/coal weightratios of 0.01/1 to 0.02/1.

Generally, in coal liquefaction processes it is most desirable from aneconomic point of view to maximize the production of gaseous and liquidhydrocarbonaceous products and to minimize the production of cokeforming materials such as asphaltenes. This is so because a gaseous orliquid hydrocarbonaceous product will generally bring a higher returnper unit of product than coke and the like.

In addition, it is desirable to minimize the amount of asphaltenespresent in a hydrocarbonaceous product which must undergo subsequentprocessing such as fractionation, solvent extraction, and the likebecause the asphaltenes themselves are difficult to process. Asphaltenestherefor render the material in which they are contained more difficultto process into the desired liquid hydrocarbonaceous products such asnaphtha, light distillate, and the like. This is also true becauseasphaltenes tend to coke under normal processing temperatures.

Therefore, in many situations it is highly desirable to minimize theasphaltenes content of the products of the coal hydrogenation operation,thereby simplifying the subsequent processing steps required for theseproducts while at the same time maximizing the amount of higher returngaseous and liquid products produced.

SUMMARY OF THE INVENTION It has now been found that the quantity ofasphaltenes present in coal liquefaction products is substantiallyreduced when the hydrogenation operation is carried out using certainsolid catalysts in the substantial absence of slurry medium and certaincatalyst/coal weight ratios.

It was surprisingly found that by hydrogenating normally solid coalaccording to this invention the asphaltenes content of the liquidproduct was more than 50 percent reduced while at the same time theamount of gaseous product and liquid light oil product and the overallconversion were all substantially increased.

Accordingly, it is an object of this invention to provide a new andimproved method for carrying out a coal hydrogenation process. it isanother object to provide a new and improved method for reducing theamount of asphaltenes contained in products from a coal liquefactionoperation. It is another object to provide a new and improved method forliquefying coal without a slurry medium. It is another object to providea new and improved method for producing liquid hydrocarbonaceousproducts from normally solid coal which products contain substantiallyreduced amounts of asphaltenes as compared to similar materials producedby the liquefaction of coal in the presence of a liquid medium.

Other aspects, objects, and advantages of this invention will beapparent to those skilled in the art from this disclosure and theappended claims.

DETAILED DESCRIPTION OF THE INVENTION According to this invention thereis provided a method wherein normally solid coal is hydrogenated underconditions to liquefy at least a portion thereof with the significantdifference that the coal hydrogenation operation itself is carried outusing certain supported solid catalysts in the substantial absence ofany externally supplied slurry medium whereby the production ofasphaltenes is reduced.

The coal hydrogenation operation generally involves mixing subdividedcoal (e.g., at least weight percent of the coal passing an eight mesh(Tyler) sieve) with molecular hydrogen in an amount sufficient toprovide a hydrogen partial pressure of from about 400 to about 8,000,preferably from about 500 to about 3,000, p.s.i.a. The overallhydrogenation operation is carried out under a temperature of from about500 to about 1,000" F. and under a total pressure of from about 400 toabout 10,000 p.s.i.g. The operation is carried out for a time sufficientto at least partially liquefy the coal, the normal reaction time beingsuch that a major amount of the solid coal is converted to gaseousand/or liquid hydrocarbonaceous products, the minor amount remaining inthe solid form being unconverted coal, ash, char, coke, and the like.

The coal hydrogenation operation is carried out in the presence of aneffective catalytic amount of a supported, solid hydrogenation catalyst.

Suitable hydrogenation catalysts include the metals, preferably insubdivided form such as powders, of iron, cobalt, nickel, vanadium,molybdenum, or tungsten, or compounds of these metals such as thehalides, oxides, sulfides, molybdates, sulfates, or oxalates. Mixturesand other combinations of two or more of these metals and/or compoundsof these metals can be employed as. desired. Exemplary materials thathave heretofore been employed as hydrogenation catalysts include thechlorides of nickel, iron, and cobalt. There can also be used sulfatesof iron, cobalt, and nickel, molybdates of cobalt, nickel, and iron,sulfides of tin, tungsten, molybdenum, or nickel, and combinationsthereof, powders of metals such as nickel, cobalt, or iron. Oxides orcombinations thereof can also be used such as oxides of iron alone or incombination with nickel oxide, oxides of tungsten alone or incombination with nickel oxide, oxides of nickel, oxides of cobalt aloneor in combination with nickel oxide, vanadium oxide, and the like.

The catalyst is supported on a carrier material such as alumina,magnesia, silica, titania, zirconia, fullers earth, kieselghur, claysuch as kaolin (Kaolinite, Halloysite, Dickite, Nacrite, and Endellite)or bentonite (Montmorillonite, Beidellite, Nontronite, Hectorite, andSaponite), attapulgite, and sepiolite, carbon, and the like. Forexample, combinations of iron oxide, alumina, and/or silica and/ortitania can be employed. Also, oxides of molybdenum, oxides of tungsten,oxides of magnesium, sulfides of tungsten, and the like can be combinedwith alumina and/or silica and/or fullers earth, and the like. Whencarbon is employed as a support it can be in the form of wood char, coalchar, activated carbon, or any other carbonaceous material containing amajor amount of carbon.

ln the above examples the iron, cobalt, and nickel can have valences oftwo or three, the vanadium a valence of five, four, three, or two, andthe molybdenum and tungsten a valence of six, five, four, three, or two.

Each support material can be employed alone or in combination with othersupport materials and is used in an amount which supports substantiallyall of the catalyst present.

Substantially any coal can be employed in this invention. For example,semianthracite, bituminous, semibituminous, subbituminous, lignite,peat, and the like can be used.

The amount of catalyst used will be an effective hydrogenation catalyticamount. The catalyst is used in a catalyst/coal weight ratio of fromabout 0.1/1 to about 2/ l preferably from about 0.5/l to about 1.5/l.

EXAMPLE 1 Two identical hydrogenation runs were carried out with theonly difference between the two being that one employed an externallysupplied hydrocarbonaceous liquid slurry medium while the other employedno such added slurry medium. In each run a commercially availablehydrogenation catalyst was used which contained 3.4 weight percent C00,13.2 weight percent M 83.4 weight percent 10,0, and 4.1 weight percentsulfur based on the total weight of the catalyst and which wassubdivided to be in the particle size range of minus 100 and plus 200mesh (U.S. sieve). The catalyst was employed in the amount of 100 weightpercent based on the total weight of the coal. The catalyst was mixedwith Pittsburgh 08 coal subdivided to be in the same particle size rangeas the catalyst. The catalyst/coal weight ratio was 1/ 1.

In both runs the coal-catalyst mixture was exposed to molecular hydrogenat a total pressure of 3,000 p.s.i.g., a temperature of 800 F. and for30 minutes. In run No. 1 there was also present 100 weight percent,based on the total weight of coal, of hydrocarbonaceous coal oil havinga boiling range of from 675 to 775 F. which had been previously obtainedfrom the hydrogenation of the same type of coal under the samehydrogenation conditions as set forth above. In run No. 2 no coal oil orother externally supplied slurry medium was employed and the dry mixtureof solid coal and solid catalyst was exposed to the hydrogen.

The gaseous and liquid products were analyzed and the results, reportedin weight percent based upon MAF coal charged, were as follows:

It can be seen from the above data that the asphaltenes content wassubstantially reduced, while the overall conversion and the amount ofgas and light coal oil were all increased.

EXAMPLE ll Pittsburgh 08 coal (minus lOO/plus 200 U.S. sieve mesh) washydrogenated with molecular hydrogen in the absence of hydrogenationcatalyst and with no added slurry medium. The coal was heated to 812 F.for 25 minutes under a maximum hydrogen pressure of 2,940 p.s.i.g. Theproducts were analyzed and the results, reported in weight percent basedupon MAF coal charged, were as follows:

TABLE ll Light Oil (boiling range under 500 F.) 2.]

Heavy Oil (boiling range over 500 F.) l6.5 Asphaltenes l 17.5 Water 3.8Percent Conversion 47.9

It can be seen from this example that a combination of presence ofsupported solid catalyst and absence of externally supplied slurrymedium is necessary to substantially reduce the asphaltenes content inthe manner done in run 2 of example l.

EXAMPLE lll TABLE Ill Gas 6.2 Light Oil (boiling range under 500 F.) IAHeavy Oil (boiling range over 500" F.) l9.4 Asphaltenes 25.0 Water 2.!Percent Conversion 48.0

It can be seen from this example that the substitution of inert solidsfor the solid catalyst does not achieve the asphaltenes reduction ofthis invention (run 2, example I).

Reasonable variations and modifications are possible within the scope ofthis disclosure without departing from the spirit and scope of thisinvention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. in a method for hydrogenating normally solid coal to liquefy at leasta portion thereof, the improvement comprising carrying out the coalhydrogenation operation in the presence of an effective catalytic amountof a solid, supported hydrogenation catalyst using a catalyst/coalweight ratio of from about 01/1 to about 2/ l, and in the substantialabsence of externally supplied liquid slurry medium, whereby theproduction of asphaltenes is reduced.

2. A method according to claim 1 wherein said hydrogenation operationcomprises mixing subdivided coal with at least one of molecular hydrogenin an amount sufficient to provide a hydrogen partial pressure of fromabout 400 to about 8,000 p.s.i.a., and maintaining the mixture under atemperature of from about 500 to about 1,500" F. and a total pressure offrom about 400 to about l0,000 p.s.i.g. for a time sufficient to atleast partially liquefy at least part of the coal.

3. A method according to claim 1 wherein said catalyst is one of Fe, Co,Ni, V, M0, or W, or the halide, oxide, sulfide, molybdate, sulfate, oroxalate of said metals or combinations of two or more of said metalsand/or said compounds thereof.

4. A method according to claim 3 wherein said catalyst is supported onat least one of alumina, silica, magnesia, zirconia, titania, clay,carbon, fullers earth or kieselghur.

5. A method according to claim 1 wherein said catalyst is sulfided C00and M00 supported on alumina.

6. A method according to claim 1 wherein said catalyst/coal weight ratiois from about 05/1 to about l.5/l.

2. A method according to claim 1 wherein said hydrogenation operationcomprises mixing subdivided coal with at least one of molecular hydrogenin an amount sufficient to provide a hydrogen partial pressure of fromabout 400 to about 8,000 p.s.i.a., and maintaining the mixture under atemperature of from about 500* to about 1,500* F. and a total pressureof from about 400 to about 10,000 p.s.i.g. for a time sufficient to atleast partially liquefy at least part of the coal.
 3. A method accordingto claim 1 wherein said catalyst is one of Fe, Co, Ni, V, Mo, or W, orthe halide, oxide, sulfide, molybdate, sulfate, or oxalate of saidmetals or combinations of two or more of said metals and/or saidcompounds thereof.
 4. A method according to claim 3 wherein saidcatalyst is supported on at least one of alumina, silica, magnesia,zirconia, titania, clay, carbon, fullers earth or kieselghur.
 5. Amethod according to claim 1 wherein said catalyst is sulfided CoO andMoO3 supported on alumina.
 6. A methOd according to claim 1 wherein saidcatalyst/coal weight ratio is from about 0.5/1 to about 1.5/1.